I really loved discovering the Winning Ways books as an undergrad: https://www.amazon.com/Winning-Ways-Your-Mathematical-Plays/dp/1568811306 https://www.amazon.

I really loved discovering the Winning Ways books as an undergrad: https://www.amazon.com/Winning-Ways-Your-Mathematical-Plays/dp/1568811306 https://www.amazon.com/Winning-Ways-Your-Mathematical-Plays/... I had the opportunity to meet him while he was at Berkeley Quantitative, and it was an honor.